Dementia had a prevalence of 13.3% and occurred at a mean age of 54.7 years. The combination of DLSQ score, age and presence of epilepsy were found to predict presence of dementia.

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Streptozotocin-induced diabetes in the rat has been shown to decrease and insulin to increase the activity of cyclic AMP phosphodiesterase (PDE) in adipose tissue. Protein activator (PA), a substance of low molecular weight, is essential for full activity of some component phosphodiesterases. A significant decrease in protein activator level (60% of control) is found in the 13,000 × g boiled supernatant from streptozotocin-diabetic rat adipose tissue. When diabetic animals are treated with insulin 24 h following the induction of diabetes, protein activator is restored to 80% of the normal control level; when diabetic animals are immediately treated with insulin, the levels of protein activator are not reduced (98% of control). Hence, insulin is capable of reversing both the decrease in protein activator and phosphodiesterase activity seen with diabetes. When partially purified supernatant from diabetic animal fat is chromatographed on a DEAE Sephacel column, the untreated diabetics show inhibition, whereas insulin-treated diabetics show maximal stimulation of the low Km cyclic AMP phosphodiesterase. Protein activator and an inhibitor are readily separated when adipose tissue homogenate is centrifuged at 13,000 × g and the boiled supernatant is passed over a DEAE Sephacel column. Diabetes is associated with a decrease in both cyclic AMP phosphodiesterase and protein activator activity, both of which are restored to normal by administration of insulin. We also report the presence of an inhibitor of activator, which is increased in streptozotocin diabetes. All of these components appear to play a role in the pathophysiology of diabetes.

As people with Down syndrome (DS) age, they are at greater risk for Alzheimer disease (AD) than the general population. It has been suggested that polymorphisms at the genes for presenilin-1 (PS-1) and alpha-1-antichymotrypsin (ACT) confer an increased risk for AD in the general population, and therefore potentially to AD in people with DS. We obtained DNA from 231 individuals with DS and 233 population controls. People with DS were evaluated for dementia. Allele frequencies at PS-1 and ACT polymorphisms in people with DS were compared to those in age-matched controls. There were no frequency differences between the control sample and DS sample for PS-1 or ACT alleles or genotypes. Similarly, there were no differences in allele frequencies between the demented and age-matched non-demented DS samples. However a higher frequency of PS-1 heterozygotes in the demented DS group was noted. We conclude that unlike the general population, neither PS-1 nor ACT polymorphisms appear to have a similar detrimental effect on dementia in DS. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 88:616-620, 1999.

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